Sulfur extraction

ABSTRACT

Sulfur extraction including provision of means for bringing molten sulfur separated from ore in close proximity to form large droplets for separation.

United States Patent Bailey Mar. 14, 1972 [54] SULFUR EXTRACTION [72] Inventor: John H. Bailey, Houston, Tex.

[73] Assignee: Allied Chemical Corporation, New York,

[22] Filed: May 21, 1970 21 App1.No.: 39,400

- 2,731,332 l/1956 Ackert ..23/308 S 2,149,373 3/1939 Vincent ..23/308 S 2,897,065 7/1959 Capell .....23/312 S 3,072,463 l/l963 Owens ..23/308 S 1,586,539 6/1926 Thornton ..23/308 S 3,551,333 12/1970 Stoddard .....23/312 S 1,841,697 1/1932 Andrews ..23/308 S FOREIGN PATENTS OR APPLICATIONS 952,502 3/ 1964 Great Britain ..23/308 S Primary ExaminerNorman Yudkoff Assistant Examiner-S. J Emery Attorney-Jonathan Plaut [57] ABSTRACT Sulfur extraction including provision of means for bringing molten sulfur separated from ore in close proximity to form large droplets for separation.

5 Claims, 2 Drawing Figures PAIENTEUMAR 14 I972 3,649,217

I0 IO INVENTOR JOHN H.BAll EY ATTORNEY SULFUR EXTRACTION BACKGROUND OF THE INVENTION This invention relates to a continuous process for recovering sulfur prills of substantial size from sulfur-bearing ore found at or brought to the surface. More specifically, sulfur is extracted from ore deposits at or near the surface by placing said ore in a column containing heated fluid therein so as to move downwardly through said fluid in a pattern in which cooperating means force the extracted, descending sulfur globules closer together for coalescence and to eliminate coalescence deterring gangue, in a manner because of the cooperation to produce larger prills of sulfur then could otherwise be produced.

This application is an improvement over applicant's U.S. application Ser. No. 826,099, filed May 20, 1969, now U.S. Pat. No. 3,556,728 issued Jan. 19, 1971.

Heretofore known methods of extracting sulfur contained in low-grade ores found at or near the surface, for example washing crushed sulfur-bearing ore in railcars with hot water to remove the sulfur have been expensive, time consuming, wasteful and therefore of peripheral utility. Such methods could not, in general, compete effectively with subsurface extraction processes employing Frasch-type techniques. A further impractical feature of prior surface recovery techniques is the extent to which they rely on batch or semibatch processing methods.

It has also been proposed to recover sulfur from crushed sulfur bearing ores by flowing them with concurrently flowing water under pressure through a conduit while subjecting them to heat to melt the sulfur. As in U.S. Pat. No. 2,537,842, issued Jan. 9, 1951, the melted sulfur, may then be quenched with cold water and globules or prills are formed. This technique has a number of disadvantages, however, relating, for example, to the pressure situation, the concurrently flowing water, the equipment and water requirement, and the size of the prills and their purity.

The present invention provides for a continuous flow of preheated, crushed, sulfurbearing ore to and through a relatively still or substantially countercurrently moving instream sulfur extraction fluid, said flow being directed by various means towards the production of prills of substantial size and high purity. More details and advantages of the present invention will become apparent upon examination of the following detailed disclosure.

SUMMARY OF THE INVENTION In accordance with the invention, crushed sulfur bearing ore, for example, crushed to a mesh size of -4, is moved by conventional means to a top of a column, for example, 200 feet high, depending on the temperature to be developed in the column, the length required in view of said temperature to keep the fluid in the column from flashing at the top thereof, the grind size of the ore originally introduced and the size sulfur globule sought to be recovered. The column is substantially filled with such fluid, for example, in the preferred embodiment, water. The water in a lower middle section of the column is heated to a temperature of 290-320 F. in one embodiment by use of, for example, a hot water jacket surrounding said column at said section. The water above said section in the column may vary in temperature from about said temperature in said previously mentioned section to about 100 F., at the top thereof. Beneath said hot water section is cold water, which is introduced at a point near the bottom of the hot water section and removed near the bottom of the column. The cold water section may have a temperature of from ambient to 150 F., and usually 100 to 150 F. The column is open to the atmosphere at the top in the preferred embodiment.

According to the present invention, the crushed, sulfurbearing ore added to the column described above settles down the column to the bottom through the water, being channeled in its flow by various cooperating flow-interrupting means to be described in detail hereinafter. The sulfur in the ore is preheated in the first section and the ore may be interrupted in its flow downward so as to be pushed closer together by baffle means. The sulfur is then melted from the ore in the hot water section previously described, which section has reached the sulfur-melting temperature desired as the result of the application of heat to the column in the area of that section and the head of water thereabove allowing for the proper pressure conditions. As the sulfur melts, the droplets of sulfur coalesce to exclude almost all other foreign material, since sulfur exhibits a tendency to agglomerate excluding all impurities. The action of the water against the settling sulfur globules, that is the action of the friction of water in relation to the settling globules impeding the descending of the globule results in further purification. A funnel at the end of the hot water section serves to bring the liquid droplets together in the hot water section, as they descend to stimulate further coalescence and larger size of the substantially pure droplet.

A screw conveyor, either manually or automatically operated, over a screen located in the hot water section enriches the sulfur by removing the larger rock, as much as 75 percent of the gangue, and, because of the angled position of the conveyor allows the liquid sulfur and fines to pass therethrough. The screen acts as the funnel in stopping flow and bringing the sulfur droplets closer together and the screw conveyor, by clearing away the gangue, allows greater contact of sulfur for large size prills and thus greater separation of the prills.

As the enlarged droplets or globules of sulfur pass into the cold fluid zone, the droplets are quenched and form separate balls (rather than grouping together) of solid sulfur. All the material (spent ore fines and sulfur) that has passed through the screen is removed from the bottom of the column, separated, and the sulfur may be further purified, if desired. Without further purifying, however, by this method sulfur of a purity of higher than about 99.5 percent may be anticipated.

In the preferred embodiment, as will be described hereinafter, the column is filled with water from the bottom of the heated section to the top of the column and such water is heated. The water may be heated by the use of a jacket external to the column filled with, for example, hot oil or other heating means. Alternatively, however, other heating means, including for example, the introduction of hot water at the bottom of the heated section and the withdrawal of the water from the top of the column, thus providing countercurrent flow of water with relation to descending crushed ore, is anticipated as an alternative. Makeup water can be added at any appropriate place in the column. for example, at the top. In any case, however, the movement of the hot water should either be relatively nonexistent in the case when (I) no water is added to these heated water sections or where only a relatively minor make up water stream is added, or (2) countercurrent, water is added to flow in a direction opposite to the movement of the incoming ore, as just described previously.

If water is added to move countercurrently to the descending ore, as described, and removed at the top of the column to be recirculated, said water will be preferably treated before being reintroduced into the boiler for heating prior to introduction into the column to remove impurities which may become present. Even where no flow of hot water into the column is anticipated, as is true in the preferred embodiment, lime may be added to the column to neutralize the acid formed in the column.

It is anticipated that at the bottom of the column cold water will exit from one side of the column and the spent ore fines and sulfur globules will be collected at and removed with cold water from the bottom of the column.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows in FIGS. 1 and 2 two schematic embodiments for carrying out the invention.

DETAILED DESCRIPTION OF EMBODIMENT Crushed ore containing sulfur of say 4 mesh, is carried to the top of a separation column 2, that column being filled with a hot fluid 3 for example, water. Said crushed ore with sulfur therein passes down through water in the first section 4 for preheating, which is in one embodiment, for example, 150 feet in height. The temperature in the preheat section 4 may extend from about the temperature at the top of the following hot water section to about for example, ambient at the top thereof. The crushed ore with sulfur passes from the preheat section into the hot water section 5, which is about 40 feet in height in this embodiment, said hot water being of the temperature of about 290320 F. In another embodiment, the temperature of the hot water in the section 5 may be considerably lower than the range just indicated, for example 260 to 290 F., and in one embodiment say 270 F., since such lower temperature, contributes to a larger size droplet of sulfur where the flow is interrupted enough to allow time for melting and coalescence.

The sulfur melts and coalesces into globules as a result of its affinity for itself and the wetting of the spent ore in comparison to the wetting of the sulfur. Section 5 of the tower 2 is heated, for example, by the use of a hot oil jacket surrounding the hot water section. The globules of sulfur passing down through the hot water are refined by their passage through the relatively still heated water to sulfur of high purity, fines of ore become disattached from said prills, which move in a teardrop aerodynamic shape during said passage. The use of a funnel 14 at the end of the hot water section 5 serves to interrupt flow of the sulfur droplets downward and bring them in closer proximity to form larger prills. At or near the end of passage through the hot water section 5, the droplets of sulfur and the gangue encounter cooperating means, made up first of a screen 15, say, for example, of 20 mesh. While the sulfur passes through the screen, the larger gangue, as much as 75 percent, is caught on top of it. Auger or screw conveyor means 16 sweeps the gangue from the screen 15 and moves it to a point where it may be disposed of, say through line 17. The angled construction of the conveyor means 16 allows the descending sulfur droplets to pass therethrough on their way through the screen. The droplets of sulfur move into the cold water section 7 immediately after encountering the funnel and cooperating means for bringing the sulfur droplets together for coalescence and removing the gangue fines, and are quenched. Adjacent the bottom of the hot water section, cold water, in the range of about ambient to l50 F., is introduced in section 7 through line 8. The cold water may be removed near the bottom of the cold water section (which is, say, feet in length) through, for example, line 9, filtered (if necessary) and recirculated through line 8, if desired. Ore fines and sulfur globules may exit through valved line 10 at the bottom of section 7. Alternatively (but now shown), ore fines may be flushed from the tower 7 through the outlet line 9 with the exiting cold water. After the ore and sulfur are flushed from the column, then the ore and sulfur globules (which may be up to 99.5 percent purity) are separated by the use of, for example, screens of say 24 and then 48 mesh. The sulfur may then be further purified, if desired.

Deflection plates 13 (FIG. 2) or other interrupting structure may be advantageously added to the column to slow down the descending movement of the ore and sulfur globules.

In FIG. 2, the same embodiment for carrying out the invention is shown as in FIG. 1, with the exception that instead of the hot jacket to provide heat to the column, hot water or steam of a temperature in the range necessary to raise the water to a sulfur melting temperature in the hot water section 5, marked zone A in FIG. 2, is introduced into the column through line 1 1.

An equivalent amount of water is extracted from the column at line 12 to provide for countercurrent flow of the heated water to the flow of the descending ore and globules.

Said extracted water through line 12 may be advantageously reheated and recirculated through line 11.

Of course, the flow of hot water shown in FIG. 2, may be combined with the use of a jacket, as shown in FIG. I, if desired; and in any event it may be desired to allow for the introduction of some make up water.

The sulfur extraction process of this invention is highly practical as the result of low utilization of water, and recirculation of that water utilized, which is especially useful in arid regions where sulfur, especially shallow deposits of sulfur may occur. Furthermore, the process is continuous with minimum use of complicated apparatus and moving parts. It is, furthermore, an extremely flexible process utilizing apparatus which may be easily changed to meet production needs, since the length of the water column and each section thereof may be varied (including using a multiple of columns) to accommodate different sulfur bearing materials and different extraction time periods.

The interaction of the funnel 14, and the cooperating means, screw conveyor 16 and screening device 15, near the end of the heated section, forces larger balls or prills of sulfur to form and that interaction is of specific importance because both the intermediate and smaller sized globules of sulfur, as well as the larger globules, are markedly increased in size thereby, leading to practical separation of the sulfur from the fines in a state of high purity.

Where desired, a closed column with a pressure valve at the top thereof may be substituted for the open column and the preheat section described above. However, it is considered extremely advantageous to use the open column described above since it is simple in construction and dispenses with all the cost, complications and danger of pressure equipment.

As mentioned previously, the fluid in the column might be other than water, for example, liquid calcium chloride. Where such other mediums are used, care must be taken to remove any contamination from the sulfur polls that may have been absorbed.

Having described my invention in detail above, I claim:

1. A method of separating sulfur from crushed ore using a standing column of water including the steps of providing a first zone in said column adjacent the top thereof of heated water below the temperature of the melting point of sulfur, introducing said ore into the top said first zone of said column for preheating said ore, providing a second zone of water in said column contiguous with and directly below said first-mentioned zone wherein the temperature is such that sulfur melts and coalesces forming liquid sulfur droplets as it passes through said second zone, moving said ore under the action of gravity alone through and from said first zone through said second zone to melt the sulfur contained therein and form said droplets, said second zone being of sufficient height to provide for purifying and enlarging said droplets through further coalescence and movement therethrough under the action of gravity through said second zone, providing a third zone of cold water at a temperature below about F. in said column contiguous with and directly below said second zone, moving said droplets under the action of gravity through said third zone to quench and thus solidify them into prills, and removing the prills, the improvement comprising providing a transverse screen across said column between said second and third zones, providing a conveying device for removal of spent ore collecting on said screen, and passing the sulfur droplets through said screen adjacent the lower end of the second zone near the upper end of the third zone.

2. A method as set forth in claim I, the improvement further comprising funneling the crushed ore and droplets to close proximity in the second zone just prior to passing it through the conveyor.

3. A method as set forth in claim 2, the improvement further comprising angling the conveyor to the horizontal for lifting the ore from the second zone.

4. A method as set forth in claim 1, the improvement further comprising providing a temperature in the second zone of about 260 to 290 F.

5. A method as recited in claim 1, further comprising providing that the column be open to the atmosphere at the end at which the crushed ore is introduced thereto.

52 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. 3,649,217 bated March 14, 1972'.

. Inventor) JOHN H. BAILEY It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 37, "75" should be 75 Claim 1, column 4, line 60, after "removing the prills" there should be added from the third zone Signed and sealed this 5th day of September l9'72.

(SEAL) Attest:

ROBERT GOTTSCHALK EDWARD PLFLETCIEHLJR.

Commissionerof Patents Attestim; Officer 

2. A method as set forth in claim 1, the improvement further comprising funneling the crushed ore and droplets to close proximity in the second zone just prior to passing it through the conveyor.
 3. A method as set forth in claim 2, the improvement further comprising angling the conveyor to the horizontal for lifting the ore from the second zone.
 4. A method as set forth in claim 1, the improvement further comprising providing a temperature in the second zone of about 260* to 290* F.
 5. A method as recited in claim 1, further comprising providing that the column be open to the atmosphere at the end at which the crushed ore is introduced thereto. 